Well, you're not alone (unfortunately) and this bug is not unique. It IS the graphics board. Actually, it's probably the VRAM on the graphics board. The problem is painfully complicated by the fact that the graphics board is on a daughter board and the VRAM is soldered permanently onto it and the graphics board is ingeniously permanently soldered onto the logic board. So, yes, you have to replace the entire logic board. Clever, huh?!?

This disaster that has befallen you has a small upside: it is a well-known and documented heat-related design error and Apple knows it. Here's a picture of my screen with fried VRAM:

My old iMac 20" G5 has gone through 4 logic boards and two power supplies and during the last failure, my screen exhibited very similar anomalies to yours. These machines run hot....very hot, hot enough to burn up components, especially if you do lots of video or Photoshop-type work. Just watching stuff on YouTube or Hulu can help boil its brains.

Now for the upside: since this is a common problem linked to a widely known Apple design flaw, you may very well be able to negotiate a free repair from Apple. Apple kept replacing boards and power supplies on my machine as late as last year though it was years out of warranty. This was by no means easy as it called for literally hours on the phone with Apple CS people. The trick here lies with whom you deal. If you go through the 'normal' customer service channels, Apple's policy is to do everything it can to blow you off citing points, normally valid, such as, "...out of warranty..this is a no-longer-supported, legacy computer....why don't you think about buying a new system?...", etc.

It's always the last one that galls me. However, since this is a design flaw you have an advantage. Firstly, you should Google around about the problem - you'll find lots of examples. This will help in your negotiations. Secondly, you MUST speak with Customer Relations. These are the only folks empowered to help you out with a remedy that doesn't involve the purchase of a new machine or a huge repair bill. These people are like gods on Olympus; if they want to they can heal the deepest wounds, making your wildest dreams come true. If you should offend them, well, woe unto you for they have hellish powers to turn you into a cow or a fruit bat, so treat them very gingerly, show proper obeisance and humility! Worship them, mortal!

Seriously, be firm but very calm and polite when you speak with them (you may have to go through several levels before you get resolution).

Here's a recent number, however it may be out of date as they seem to change numbers with uncanny frequency: (800) 409-5381. If this number doesn't work, just go through customer service and firmly insist on speaking with someone in Customer Relations. Good luck! All Power To The Peephole!

As far as getting Apple to replace it out of warranty..... if you don't get the answer you are looking for, say Thank You, hang up and call back later. I have received much better service with another call and another rep sometimes.

Also, I was saying to boot the iMac from the suspect drive while in FW target disk mode. Your healthy Mac can see the problem Macs OS and boot from it. If it boots fine then you KNOW it's a video problem. Which we already know now... but in the future, that's a great way to narrow it down.

Oh yeah... look for a thread by me recently where I got my logic and vid boards replaced for free out of warranty due to a well known and documented problem.Alec/Mississauga too.

"If it turns out that President Barack Obama can make a deal with the most intransigent, hard-line, unreasonable, totalitarian mullahs in the world but not with Republicans? Maybe he’s not the problem."

Here's a recent number, however it may be out of date as they seem to change numbers with uncanny frequency: (800) 409-5381. If this number doesn't work, just go through customer service and firmly insist on speaking with someone in Customer Relations. Good luck! All Power To The Peephole!

This number asks for an extension number...so I'm having to go through regular Apple customer service

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